MB 1

T.O.F. IIT.O.F. IIPrecise timingPrecise timing

Electron IDElectron IDEliminate muons Eliminate muons that decay that decay

Tracking devicesTracking devices

T.O.F. 0 & IT.O.F. 0 & IPion /muon Pion /muon IDIDprecise precise timingtiming

201 MHz RF cavities

Liquid H2 absorbersor LiH ?SC Solenoids;

Spectrometer, focus pair, compensation coil

TOF 0, I-II positions

1. Trigger

2. PID

3. Timing respect to RF

TOF system in MICE

MB 2

Tof detector structureConventional fast scintillator bars, read by PMTs at both ends, arranged in planes (Y or X/Y for better performances) for 3 stations: T0,T1,T2Aimed performance 70 psBars are staggered and overlapped at the edges (for cross calibrations with incoming particles) Calibration: beam particles impinging on overlaps + dedicated fast laser system (a la Harp)

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A layout of the Laser calibration system (Harp system)

Laser Nd-YAG with passive Q-switch (dye), active/passive mode locking and 10 Hz repetition rateIR emission converted to a second harmonic (=532 nm) by a KD*P SHG crystal

Pulse: width 60 ps energy 6

mJBeam splitter:To ultra-fast (30 ps rise/fall) InGaAs MSM photodiode = STARTTo detector slabs through custom-made optical fibre system = STOP

Foreseen mod: introduction of an optical switch to deliver signal to single channel

MB 4

Main experimental problems:

T0: high incoming particle rate (at least some MHz). Solution: R4998 PMTs with modified divider circuit (it can sustain up to 1.6 MHz, but small tolerance to B fiels) T1,T2: high magnetic fields. Solution: global iron shield+ fine-mesh PMTs (R7761, R5505)Tests under way: laboratory rate tests for PMTs, fine-mesh PMTs tests in B field

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PMT rate studies

Hamamatsu PLP-10 fast laser (35 FWHM, 1Hz-1MHz rate, 415 nm) Fiber launching system into IR multimode fiber (Ceram OPTEC UV 50/100, measured spread 15 ps/m)PMT signal read by QVT (35 ps resolution)

R4998 with modified divider circuit: booster

for last dynodes

Lab rate tests to be done with:

Nominal: up to 1.5 MHz

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Preliminary rate effects tests

Please insert here .prn file available

MB 7

PMTs for TOF1,TOF2: problems with high magnetic field

Figure shows |B| from the cooling and measurement solenoids.The phototubes are placed in a place with high field. B may be bigger

than 1 T -> problems

TOF II ?

Fine-mesh PMTs may not be enough

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First step: global soft iron shield for downstream detector (GG)

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Solution from Ghislain: single iron slab 15-cm thick with a central hole of 40 cm-diameter

Z (cm)

r (cm)

Field map covers the domain 0 < z < 135 cm and 0 < r < 100 cm (dashed rectangle)

O

B is greatly reduced well below 1 T

No problemfor PMTs

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Second step: systematic fine-mesh PMTs test in B-field (up to 1.2T)

PMT under test

Light source:

Laser diode Hitachi DL3038-011 (635nm) pulsed by a pulser

(Lecroy 9210, risetime 300 ps) FWHM laser pulse 300 ps.

Injection in a short optical fiber to a prism, giving light to the PMTOutput PMT signal to a Silena QVT

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Fine-mesh phototube Properties

Under test

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Test magnet at LASA. First typical results.

1. Timing measurements2. Gain measurements

As a function of B,More measurements under way